HYBRID EXCEEDED ROTATING MACHINE

Abstract

The electrified powertrain of a vehicle includes a battery pack connected to a traction power inverter module (TPIM), which converts a direct current (DC) voltage from the battery pack to alternating current (AC). A rotating electric machine includes a stator, which is excited by the AC voltage from the TPIM, and enclosing a rotor core that can rotate. The rotor core contains recesses that hold conductive bars and permanent magnets, with the conductive bars positioned closer to the center of the rotor core. The conductive bars and permanent magnets are separated by gaps in each recess. An annular end ring assembly is present at one end of the rotor core and has connecting conductors that are connected to subsets of conductive bars and a secondary coil of a rotary transformer. When the stator is excited, the rotor shaft, which is connected to the rotor, rotates.The electric machine drives a gearbox that is coupled to the rotor shaft.

Description

[0001] The disclosure relates to rotating electrical machines. In particular, the disclosure relates to hybrid-excited (HE) rotating machines that combine permanent magnet (PM) excitation and field excitation.

[0002] HE machines advantageously provide two sources of rotor magnetic fields. The rotor in such machines may typically contain field coils wound from low-gauge wires, limiting the fill factor and adding complexity to rotor manufacturing. HE machines can exhibit relatively high heat and a potential for heat-induced demagnetization and decreasing field strength of the permanent magnets, partly due to the additional copper loss characteristics of field coils.

[0003] HE machines that have a high fill factor, easier manufacturing, and heat tolerance characteristics are desirable. SUMMARY

[0004] In an exemplary embodiment, an electric machine may include a stator and a rotor core surrounded by the stator and rotatable about an axis, the rotor core having axially opposite ends and a plurality of recesses, each recess extending through the rotor core between the axially opposite ends and containing at least one respective electrical conductor and at least one respective permanent magnet, the electrical conductors being radially inward of the permanent magnets and extending beyond the axially opposite ends of the rotor core.

[0005] In addition to one or more of the features described herein, the electrical conductors may include conductive rods.

[0006] In addition to one or more of the features described herein, the conductive rods may include hairpin conductors.

[0007] In addition to one or more of the features described herein, the at least one respective electrical conductor and the at least one respective permanent magnet contained in each recess may be separated by a respective space.

[0008] In addition to one or more of the features described herein, the at least one respective permanent magnet included in each recess may include a stack of permanent magnets.

[0009] In addition to one or more of the features described herein, the at least one respective permanent magnet included in each recess may include a respective first magnet and a respective second magnet, the first magnets being located between the second magnets and the electrical conductors, the first magnets having a first temperature rating and the second magnets having a second temperature rating less than the first temperature rating.

[0010] In addition to one or more of the features described herein, the at least one respective permanent magnet included in each recess may include a respective first magnet and a respective second magnet, the first magnets being located between the second magnets and the electrical conductors, the first magnets having a first coercive field strength and the second magnets having a second coercive field strength that is less than the first coercive field strength.

[0011] In addition to one or more of the features described herein, the spaces separating the electrical conductors and the permanent magnets may include cooling passages in the rotor core.

[0012] In addition to one or more of the features described herein, the spaces separating the electrical conductors and the permanent magnets may contain a thermal insulator.

[0013] In addition to one or more of the features described herein, the conductive rods may be hollow.

[0014] In addition to one or more of the features described herein, the recesses may be open at a circumference of the rotor core sufficiently for radial insertion of the electrical conductors.

[0015] In addition to one or more of the features described herein, the electric machine may further include a cylindrical containment sleeve surrounding the rotor core at a periphery of the rotor core.

[0016] In addition to one or more of the features described herein, the electric machine may further include an annular end ring assembly at one end of the rotor core including a first terminal conductor galvanically coupled to a first subset of the conductive bars and a second terminal conductor galvanically coupled to a second subset of the conductive bars.

[0017] In addition to one or more of the features described herein, the annular end ring assembly may further include a secondary coil of a rotary transformer.

[0018] In addition to one or more of the features described herein, the annular end ring assembly may radially surround the conductive rods, extending beyond one end of the rotor core.

[0019] In addition to one or more of the features described herein, the annular end ring assembly may be radially surrounded by the conductive rods extending beyond one end of the rotor core.

[0020] In another exemplary embodiment, an electric machine may include a stator, a rotor core surrounded by the stator and rotatable about an axis, the rotor core having axially opposite ends and a plurality of recesses, each recess extending through the rotor core between the axially opposite ends and containing at least one respective conductive bar and at least one respective permanent magnet, the conductive bars being radially inward of the permanent magnets and extending beyond the axially opposite ends of the rotor core, and the at least one respective conductive bar and the at least one respective permanent magnet contained in each recess being separated by a respective space, and an annular end ring assembly at one end of the rotor core including a first terminal conductor galvanically coupled to a first subset of the conductive bars,and a second connecting conductor galvanically coupled to a second subset of the conductive rods.

[0021] In addition to one or more of the features described herein, the annular end ring assembly may further include a secondary coil of a rotary transformer.

[0022] In addition to one or more of the features described herein, the at least one respective permanent magnet included in each recess may include a respective first magnet and a respective second magnet, the first magnets being located between the second magnets and the conductive rods, the first magnets having a first coercive field strength, and the second magnets having a second coercive field strength that is less than the first coercive field strength.

[0023] In yet another exemplary embodiment, an electrified powertrain for a vehicle may include a battery pack, a traction power inverter module (“TPIM”) connected to the battery pack and configured to change a direct current (“DC”) voltage from the battery pack to an alternating current (“AC”) voltage, and a rotating electric machine including a stator excited by the alternating current from the TPIM, a rotor core surrounded by the stator and rotatable about an axis, the rotor core having axially opposite ends and a plurality of recesses, each recess extending through the rotor core between the axially opposite ends and including at least one respective conductive bar and at least one respective permanent magnet,the conductive bars are radially inward with respect to the permanent magnets and extend beyond the axially opposite ends of the rotor core, and the at least one respective conductive bar and the at least one respective permanent magnet contained in each recess are separated by a respective space, and an annular end ring assembly at one end of the rotor core including a first lead galvanically coupled to a first subset of the conductive bars and a second lead galvanically coupled to a second subset of the conductive bars, the annular end ring assembly further including a secondary coil of a rotary transformer for energizing the conductive bars, a rotor shaft connected to the rotor and configured to rotate about an axis of rotation in conjunction with the rotor when the stator is energized, and a gearbox,which is coupled to the rotor shaft and is supplied with energy by the electric machine.

[0024] The above-described features and advantages and other features and advantages of the disclosure will become apparent from the following detailed description when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Further features, advantages and details appear only as examples in the following detailed description, which refers to the drawings; they show: Fig. 1 an electrified powertrain according to one or more embodiments; Fig. 2 illustrates various features of a hybrid electric machine rotor according to one or more embodiments; Fig. 3A and Fig. 3B illustrates various features of a hybrid electric machine rotor according to one or more embodiments; Fig. 4 illustrates various end features of a hybrid electric machine rotor according to one or more embodiments; Fig. 5A and Fig. 5B illustrates various magnetic operations of a hybrid electric machine rotor according to one or more embodiments; and Fig. 6 an alternative structure of a hybrid electric machine rotor according to one or more embodiments. DETAILED DESCRIPTION

[0026] The following description is merely exemplary in nature and is not intended to limit the present disclosure, its application, or uses. Throughout the drawings, corresponding reference characters indicate similar or corresponding parts and features. A description of parts and features in one drawing will be understood to apply to parts and features in other drawings that share the same reference characters, to the extent that such parts and features are not otherwise distinguishable by drawing examination by one of ordinary skill in the art or distinguished by additional written description herein.

[0027] With reference to the drawings, wherein like reference numerals refer to the same or similar components throughout the several figures, Fig. 1 schematically illustrates an electrified powertrain 10 (e.g., for use in an exemplary motor vehicle 11). The powertrain 10 includes a rotating electric machine 12 having a rotor 12R and a stator 12S. The rotor 12R may include internal permanent magnets and direct current (DC) field windings as sources of rotor magnetic fields. When the stator 12S is energized, the rotor 12R provides motor torque to a transmission 20 (e.g., a stepped automatic transmission).

[0028] Although omitted for simplicity of illustration, the electrified powertrain 10 may also include an internal combustion engine configured to generate engine torque. In such an arrangement, the generated engine torque may be selectively delivered to the transmission 20 either alone or in conjunction with the engine torque from the electric machine 12.

[0029] If the vehicle 11 of Fig. 1 is embodied as a hybrid electric vehicle, the electric machine 12 and / or the prime mover may power the transmission 20. Alternatively, the vehicle 11 may be a battery electric vehicle, in which case the transmission 20 may be powered solely by engine torque from the electric machine 12. The disclosed improvements relate to the design of the electric machine 12 and may be implemented in hybrid electric vehicle (HEV) and electric vehicle (EV) embodiments of the vehicle 11 without limitation, as well as in non-vehicle applications such as power plants, hoists, mobile platforms, and robots, etc.

[0030] With continued reference to the exemplary vehicle 11 of Fig. 1, the electrified powertrain 10 may include an alternating current (AC) bus 13. The AC bus 13 may be selectively excited by a traction power inverter module (TPIM) 28 that is DC coupled to a high-voltage (HV) battery pack 24, such as a lithium-ion, lithium-sulfur, nickel-metal hydride, or other high-energy voltage supply. The AC bus 13 provides an alternating current (VAC) bus voltage and carries an alternating current to or from the electric machine 12. Motor torque from the excited electric machine 12, when operating in a drive or motor mode, is communicated to a rotor shaft 125 of the rotor 12R, the rotor shaft 125 being journalled, splined, or otherwise connected to the rotor 12R. The motor torque is then communicated to a coupled load, such as a B. the gearbox 20 and / or one or more impellers 22.

[0031] The HV battery pack may be DC-coupled to the TPIM 28 via a relatively high DC voltage bus (e.g., a DC link) 15 at a relatively high DC voltage (VDC). The electrified powertrain 10 may also include a DC-DC converter 26 configured to decrease or increase a relatively high DC bus voltage VDC as needed. The DC-DC converter 26 is connected between the battery pack 24 and a relatively low DC voltage bus 16. In certain configurations, an auxiliary battery pack 124 may be connected to the DC-DC converter 26 via the relatively low DC voltage bus 16. The auxiliary battery pack 124 may be embodied as a lead-acid battery or a battery constructed and configured from another chemistry suitable for applications, e.g., a 12-15 V auxiliary voltage (V AUX) or to deliver it to one or more connected auxiliary devices (not shown).

[0032] The rotor 12R of the electric machine 12 is positioned adjacent to the stator 12S and separated from it by an air gap. The stator 12S and the rotor 12R may be constructed from a stack of thin laminations (e.g., electrical steel or another ferrous material, with each lamination typically being about 0.2 mm - 0.5 mm thick, as recognized by those skilled in the art). Laminations may be cut to their final shape by a punch and die, or may be cut by a laser or wire EDM.

[0033] The rotor 12R, which is in Fig. 1, includes internal rotor recesses characterized by cavities in the electrical steel of the laminations. Such rotor recesses may provide a flux barrier in rotor 12R and may include other rotor features as further described herein. According to certain embodiments, the rotor recesses may be partially or fully filled with a combination of permanent magnets (PM) and electrical conductors. The electrical conductors of rotor 12R act as field windings to strategically generate magnetic fields in rotor 12R. The electrical conductors may be energized by a DC power source, e.g., from the relatively high DC voltage bus 15 via a rotary transformer 29.

[0034] Fig. 2 shows an exemplary rotor core 201 of the rotor 12R of Fig. 1 according to a hybrid excited (HE) rotating machine. The representation in Fig. 2 represents one half of a rotor core 201, which is divided by the rotational axis 203 of the rotor 12R for simplicity and clarity of illustration. The rotor core 201 may be constructed from a stack of thin laminations (e.g., electrical steel or another ferrous material, with each lamination typically being about 0.2 mm-0.5 mm thick, as will be recognized by those skilled in the art). Laminations may be cut to their final shape by a punch and die, or may be cut by a laser or wire EDM. The rotor core 201 may alternatively be fabricated, e.g., cast, from sintered metal powder and binder under heat and pressure. The stator, according to a non-limiting exemplary embodiment, is concentrically disposed around the rotor 12R such that the rotor 12R is surrounded by the stator 12S.In such embodiments, the air gap G is a radial air gap, and the electric machine 12 embodies a radial flux type machine. However, other embodiments may be realized wherein the relative positions of the rotor 12R and stator 12S are reversed. For consistency of illustration, the embodiment of FIG. 1 is used here. Fig. 1, wherein the rotor 12R is located radially in the stator 12S, without limiting the design to such a configuration.

[0035] The Stator 12S from Fig. 1 is not illustrated in greater detail, but may include radially projecting stator teeth extending inward from a cylindrical stator core. That is, the stator teeth extend from the stator core to the rotor 12R. The inner diameter surface of the stator 12S is the radially innermost surface of the stator teeth, facing or opposing the outer peripheral surface 205 of the rotor 12R in spaced proximity to form the air gap G (see Fig. 1). Adjacent stator teeth are separated from each other by a corresponding stator recess, as recognized by those skilled in the art. The stator recesses enclose electrical conductors, typically copper wires, copper bars, or hairpin conductors. Such conductors collectively form stator windings. A rotating stator magnetic field is generated when the stator windings are energized by a multiphase output voltage from the TPIM 28 of Fig. 1 are sequentially excited. Stator magnetic poles formed from the resulting rotating stator magnetic field interact with rotor poles to rotate the rotor 12R about the rotation axis 203.

[0036] In the embodiment of a rotating HE machine from Fig. 2, the rotor core 201 may include a number of recesses 207 extending axially through the rotor core 201 between opposite ends 209 of the rotor core 201. The recesses may be substantially axially aligned between the opposite ends 209 of the rotor core, although the actual alignment may be twisted, as is known in the art. The recesses 207 may be substantially radially aligned, although the actual alignment may be offset from a true radial alignment, as is known in the art. Reference herein to a radial alignment or a substantially radial alignment of recesses, permanent magnets, or electrical conductors is understood to refer to the true radial alignment or a twisted radial alignment, as is known to those skilled in the art.In one embodiment, each recess 207 may include an electrical conductor 211 and a permanent magnet 213. The permanent magnets 213 may be continuous or segmented along the axial length of the recesses 207. The electrical conductors 211 are continuous along the axial length of the recesses 207 and may extend axially beyond the opposite ends 209 of the rotor core 201, as at one end 209 of FIG. Fig. 2. The electrical conductors 211 and the permanent magnets 213 are arranged in the recesses 207 such that the electrical conductors 211 are located below or radially inwardly relative to the permanent magnets 213.

[0037] The permanent magnets 213 may be referred to collectively herein as rotor magnets and may be constructed, for example, from ferrite, neodymium iron boron, samarium cobalt, aluminum nickel cobalt, etc., or another material suitable for applications, as may be discussed in more detail herein. The rotor magnets in such an embodiment are embedded in respective recesses 207 in the stack of individual steel laminations of the rotor core 201. The number, type, position, and / or relative orientation of the rotor magnets ultimately influences the magnitude and distribution of the magnetic flux in the ferrous materials of the electric machine 12. In addition, when viewed axially (e.g., Fig. 3A and Fig. 3B) The rotor magnets are evenly distributed circumferentially. In one embodiment, the poles of the rotor magnets can be axially aligned. In one embodiment, the poles of the rotor magnets can be circumferentially aligned. In one embodiment, the poles of the rotor magnets can be radially aligned.

[0038] Fig. 3A and Fig. 3B represent a side view of the rotor core viewed along the rotation axis 203 shown in Fig. 2 is illustrated. Fig. 3A and Fig. 3B illustrate a number of different embodiments of structures of recess 207, electrical conductors 211, and permanent magnets 213. Fig. 3A essentially illustrates exemplary embodiments of various arrangements of an electrical conductor 211 and a permanent magnet 213 aligned in truly radially aligned recesses 207. Fig. 3B essentially illustrates exemplary embodiments of various radial and twisted radial recesses 207 and orientations of an electrical conductor 211 and a permanent magnet 213.

[0039] In Fig. 3A, recess positions are labeled A through G for easy reference to the various exemplary embodiments. Beginning with recess position A, recess 207 contains an assembly of a permanent magnet 213 and an electrical conductor 211 radially inward from permanent magnet 213. A space 301 separates permanent magnet 213 and electrical conductor 211. Electrical conductor 211 is shown as a single conductive rod. The conductive rod may be any suitable conductor, such as, but not limited to, copper, aluminum, or brass. Conductive rods may be manufactured using any suitable process, including, but not limited to, stamping, rolling, laser cutting, casting, extrusion, etc. In the embodiment, at recess position A, the conductive rod is solid. Space 301 may be an air gap or may be filled with an insulator, such as,Mineral wool or polyurethane. The space 301 can also provide a channel for circulating a pressurized coolant, such as lubricating oil or air. The recess 207 at position A is a closed recess that includes a bridge 303 made of a material from rotor cores 201 at the outer peripheral surface 205 of the rotor core 201. The bridge 303 in the embodiment at recess position A can preclude radial insertion of the electrical conductor 211 and the permanent magnet 213, thus limiting the manufacture of rotor cores 201 to axial insertion.

[0040] At recess position B, the recess 207 contains an assembly of a permanent magnet 213 and an electrical conductor 211 radially inward from the permanent magnet 213. A space 301 separates the permanent magnet 213 and the electrical conductor 211. The electrical conductor 211 is shown as a single conductive rod. The conductive rod may be any suitable conductor, such as, but not limited to, copper, aluminum, or brass. Conductive rods may be manufactured using any suitable process, including, but not limited to, stamping, rolling, laser cutting, casting, extrusion, etc. In the embodiment, at recess position B, the conductive rod is hollow and has a central channel 305 therethrough. The channel may carry a pressurized coolant, such as lubricating oil or air. The space 301 may be an air gap or may be filled with an insulator, such asMineral wool or polyurethane. The space 301 may also provide a channel for circulating a coolant, such as a lubricating oil. The recess 207 at position B is an open recess having a discontinuity 307 in the bridge of rotor core material 201 at the outer peripheral surface 205 of the rotor core 201. The discontinuity 307 in the embodiment at recess position B may be too small for radial insertion of the electrical conductor 211 and the permanent magnet 213, thus limiting the fabrication of rotor cores 201 to axial insertion.

[0041] At recess position C, the recess 207 contains an arrangement of a permanent magnet 213 and an electrical conductor 211 radially inward of the permanent magnet 213. A space 301 separates the permanent magnet 213 and the electrical conductor 211. The electrical conductor 211 is shown as a first conductive rod 211A and a second conductive rod 211B. The conductive rods may be any suitable conductor, such as, but not limited to, copper, aluminum, or brass. Conductive rods may be manufactured using any suitable process, including, but not limited to, stamping, rolling, laser cutting, casting, extrusion, etc. In the embodiment, at recess position C, the conductive rods are solid. The space 301 may be an air gap or may be filled with an insulator such as mineral wool or polyurethane. The space 301 may also include a channel for circulating a coolant such asof a lubricating oil. The recess 207 at position C is an open recess that includes a discontinuity 309 in the bridge of material of rotor cores 201 at the outer peripheral surface 205 of the rotor core 201. The discontinuity 309 in the embodiment at the recess position C may be large enough for radial insertion of the electrical conductor 211 and the permanent magnet 213. In one embodiment, a non-magnetic cylindrical sleeve 310 may surround the rotor core 201 if the discontinuity 309 does not provide retention features over the permanent magnet 213.

[0042] At recess position D, recess 207 contains an arrangement of a permanent magnet 213 and an electrical conductor 211 radially inward from permanent magnet 213. A space 301 separates permanent magnet 213 and electrical conductor 211. Electrical conductor 211 is shown as a plurality of electrical conductors 211, such as hairpin conductors. The hairpin conductors may be any suitable conductor, such as, but not limited to, copper, aluminum, or brass. Hairpin conductors may be manufactured using any suitable process, including, but not limited to, extrusion, molding, etc. In the embodiment, at recess position D, the hairpin conductors are solid. Space 301 may be an air gap or may be filled with an insulator, such as mineral wool or polyurethane. Space 301 may also provide a channel for circulating a coolant, such as a lubricating oil.The hairpin conductors may be inserted radially or axially depending on the existence and size of any interruption of the bridge of the material of rotor cores 201 at the outer peripheral surface 205 of the rotor core 201.

[0043] At recess position E, recess 207 contains an arrangement of a permanent magnet 213 and an electrical conductor 211 radially inward from permanent magnet 213. A space 301 separates permanent magnet 213 and electrical conductor 211. Electrical conductor 211 is shown as a single conductive rod. The conductive rod may be any suitable conductor, such as, but not limited to, copper, aluminum, or brass. Conductive rods may be manufactured using any suitable process, including, but not limited to, stamping, rolling, laser cutting, casting, extrusion, etc. In the embodiment, at recess position E, the conductive rod is fixed. A closed channel 311 is formed in rotor core 201 in space 301 between electrical conductor 211 and permanent magnet 213. The closed channel 311 may be a channel for circulating a pressurized coolant such as water.B. a lubricating oil or air. The conductive rod and the permanent magnets 213 can be inserted radially or axially depending on the existence and size of any discontinuity in the bridge of a material of rotor cores 201 at the outer peripheral surface 205 of the rotor core 201.

[0044] At recess position F, recess 207 contains an arrangement of a permanent magnet 213 and an electrical conductor 211 radially inward from permanent magnet 213. A space 301 separates permanent magnet 213 and electrical conductor 211. Electrical conductor 211 is shown as a single conductive rod. The conductive rod may be any suitable conductor, such as, but not limited to, copper, aluminum, or brass. Conductive rods may be manufactured using any suitable process, including, but not limited to, stamping, rolling, laser cutting, casting, extrusion, etc. In the embodiment, at recess position F, the conductive rod is fixed. A closed channel 313 is disposed in rotor core 201 in space 301 between electrical conductor 211 and permanent magnet 213.The closed channel 313 may be a conduit or pipe of any suitable cross-section. The closed channel 313 may provide a channel for circulating a pressurized coolant, such as lubricating oil or air. The conductive rod and permanent magnets 213 may be inserted radially or axially, depending on the existence and size of any discontinuity in the bridge of a material of rotor cores 201 at the outer peripheral surface 205 of the rotor core 201.

[0045] At recess position G, recess 207 includes an arrangement of a permanent magnet 213 and an electrical conductor 211 radially inward of permanent magnet 213. Permanent magnet 213 is shown as a first permanent magnet 213A and a second permanent magnet 213B. First permanent magnet 213A is located between second permanent magnet 213B and electrical conductor 211. In one embodiment, first permanent magnet 213A may have a first temperature rating that is less than the temperature rating of second permanent magnet 213B. In one embodiment, first permanent magnet 213A may have a first coercive field strength that is less than the coercive field strength of second permanent magnet 213B. A space 301 separates permanent magnet 213 and electrical conductor 211. Electrical conductor 211 is shown as a single conductive rod.The conductive rod may be any suitable conductor, such as, but not limited to, copper, aluminum, or brass. Conductive rods may be manufactured using any suitable process, including, but not limited to, stamping, rolling, laser cutting, casting, extrusion, etc. In the embodiment, at the recess position G, the conductive rod is fixed. The space 301 may be an air gap or may be filled with an insulator such as mineral wool or polyurethane. The space 301 may also provide a channel for circulating a pressurized coolant, such as a lubricating oil or air. The conductive rod and the permanent magnets 213 may be inserted radially or axially, depending on the existence and size of any discontinuity in the bridge of a material of rotor cores 201 at the outer peripheral surface 205 of the rotor core 201.

[0046] In Fig. 3B, adjacent sets of magnets 213 and electrical conductors 211 are labeled 325, 335, 345, and 355 for easy reference to the various exemplary embodiments. The sets may, for example, correspond to pole pairs found in rotors with internal permanent magnets. The dashed lines correspond to radii through the rotor core 201 that correspond to the general positional distribution of a pair of a permanent magnet 213 and an electrical conductor 211 on one side of a set providing a pole pair, as described. The recesses 207 are illustrated as containing a respective space 301. Recesses may be formed with protrusions for supporting the permanent magnets 213 and the electrical conductors 211, as shown in exemplary embodiments of sets 325 and 335.Recesses may be formed without protrusions for supporting the permanent magnets 213 and the electrical conductors 211, as shown in exemplary embodiments of sets 345 and 355. Set 325 represents a pair of magnets 213 that are radially twisted and a pair of electrical conductors 211 that are also radially twisted. In set 325, the pairs of a permanent magnet 213 and an electrical conductor are twisted by a corresponding angle. Set 335 represents a pair of magnets 213 that are truly radially aligned and a pair of electrical conductors 211 that are radially twisted. Set 345 represents a pair of magnets 213 that are radially twisted and a pair of electrical conductors 211 that are truly radially aligned. Set 355 represents a pair of magnets 213 that are radially twisted and a pair of electrical conductors 211 that are also radially twisted.In set 355, the permanent magnets 213 are twisted at a larger angle than the electrical conductors 211.

[0047] The general design of a rotating HE machine from Fig. 2, wherein the electrical conductors 211 are continuous conductive rods over the axial length of the recesses 207 and extend axially beyond the opposite ends 209 of the rotor core 201, is used for the purpose of the following description of the embodiments of Fig. 4. In one embodiment, an annular end ring assembly 401 may include two or more connecting conductors 403 for galvanically coupling to respective subsets of the conductive rods 211. The connecting conductors 403 may, for example, be formed as copper end rings with radially extending features that are galvanically coupled to subsets of the conductive rods, as shown in Fig. 4. Such copper end rings may be axially stacked and separated by insulating rings. A permanent connection between the copper end rings and the conductive rods may be in the form of soldering, brazing, laser welding, etc. The end ring assembly 401 is shown as extending radially outward from and surrounding the conductive rods, although an alternative arrangement is illustrated as an annular end ring assembly 407 surrounded by the conductive rods. In embodiments wherein the electrical conductors are hairpin conductors, the hairpin conductors may be pre-formed prior to insertion, thus obviating the need for a trace end ring at one end of the rotor core. However, an end ring, even on the pre-formed side, may benefit from structural reinforcement of a non-conductive end ring assembly.In one embodiment, both arrangements of end ring assemblies 401 and 407 may be employed. The end ring assemblies may incorporate a secondary coil 409 of a rotary transformer for supplying electrical power to the electrical conductors 211 to generate a desired magnetic field response to current flow through the electrical conductors 211. A stationary main winding (not shown) may inductively connect electrical power to the secondary coil 409 in one or both of the end ring assemblies. Using the end ring assembly 407 may advantageously support a compact rotary transformer, where the primary coil may be directed radially inward from the secondary coil 409. A similar end ring assembly 406 may be used on the opposite axial side of the rotor to short-circuit all of the electrical conductors 211 or separate subsets to add flexibility and degrees of freedom.

[0048] Fig. 5A and Fig. 5B illustrate an exemplary rotor core 201 and a plurality of electrical conductors 211 and permanent magnets 213, as previously set forth herein. In the illustrated embodiment, the exemplary permanent magnet has a north pole (N-pole) and a south pole (S-pole) that are circumferentially aligned, as shown. In operation, the magnetic field from the permanent magnets 213 includes PM flux paths 503 between the magnetic poles that include radially aligned components, as illustrated. The radially aligned PM flux paths 503 may include radially outward paths that intersect the air gap G and radially inward paths through the magnetic return path 507 of the rotor core 201. The exemplary energized electrical conductor 211 may selectively conduct current from the side ( Fig. 5A) or into the side ( Fig. 5B), resulting in the electromagnetic field (EM field) from the exemplary electrical conductor 211 shown in the EM flux paths 505 around the electrical conductors 211 according to the right-hand rule. In Fig. 5A, with current through the exemplary excited electrical conductor 211 from the side, the EM field is in the same direction as the PM field in the air gap G, resulting in a net magnetic field enhancement through the air gap G. In Fig. 5B, with current flowing through the exemplary energized electrical conductor 211 into the side, the EM field is in the opposite direction as the PM field in the air gap G, resulting in a net magnetic field attenuation across the air gap G.

[0049] Fig.6 illustrates an alternative embodiment of a rotor core 201 that resembles a wound salient-pole rotor. Recesses 207 are shown on each side of a separator 601 and defined between the separator 601 and the rotor core 201. As shown, the cross-section of the recesses 207 may open into the air gap. Thus, to increase the fill factor, the recesses 207 may contain a plurality of electrical conductors 211 of different cross-sections. The electrical conductors may be bar steel containing hairpin conductors or may be wound wire, with the separator 601 providing a winding post. The permanent magnets 213 may have the poles radially aligned, as shown. The magnetic field in the air gap G may be selectively strengthened or weakened by the current direction through the electrical conductors 211.The permanent magnets 213 may have a single rectangular cross-section, as illustrated, or may be trapezoidal or stacked in multiple pieces of different cross-sections similar to electrical conductors to improve the fill factor.

[0050] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will further be understood that the terms "comprises" and / or "comprising," when used in this application text, specify the presence of specified features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and / or groups thereof.

[0051] All numerical values ​​are assumed to be modified by the term "about," whether expressly stated or not. For the purposes of the present disclosure, ranges may be expressed as from "about" one particular value to "about" another particular value. The term "about" generally refers to a range of numerical values ​​that one skilled in the art would consider equal to the recited numerical value, to have the same function or result, or to generally be reasonably within manufacturing tolerances of the recited numerical value. Accordingly, numerical values ​​set forth herein are by way of non-limiting examples and may be nominal values, it being understood that actual values ​​may vary from nominal values ​​according to environment, design and manufacturing tolerances, age, and other factors.

[0052] When an element, such as a layer, lamina, region, or substrate, is referred to as being "on" another element, it may be disposed directly on the other element, or there may also be intervening elements. Conversely, when an element is referred to as being "directly on" another element, there are no intervening elements. Therefore, unless expressly described as "direct," when a relationship between a first and a second element is described above in the disclosure, that relationship may be a direct relationship, with no other intervening elements between the first and second elements, but may also be an indirect relationship, with one or more intervening elements (either spatial or functional) between the first and second elements.

[0053] One or more steps in a method may be performed in different orders (or overlapping in time) without altering the principles of the present disclosure. Furthermore, although each of the embodiments has been described above with certain features, one or more of those features described with respect to any embodiment of the disclosure may be implemented in any of the other embodiments and / or combined with their features, even if that combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and permutations of one or more embodiments with one another remain within the scope of this disclosure.

[0054] Unless otherwise defined, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0055] Unless otherwise specified herein, all examination standards shall be the most recent standard in force as of the filing date of this application or, if priority is claimed, the filing date of the earliest priority application in which the examination standard appears.

[0056] While the above disclosure has been described with reference to exemplary embodiments, those skilled in the art will understand that various changes may be made and equivalents may be substituted for elements without departing from the scope thereof. Additionally, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from its essential scope. Therefore, it is intended that the present disclosure not be limited to the particular embodiments disclosed, but will include all embodiments falling within its scope.

Claims

[1] Electrical machine comprising: a stator and a rotor core surrounded by the stator and rotatable about an axis, the rotor core having axially opposite ends and a plurality of recesses, each recess extending through the rotor core between the axially opposite ends and containing at least one respective electrical conductor and at least one respective permanent magnet, the electrical conductors being radially inward of the permanent magnets and extending beyond the axially opposite ends of the rotor core. [2] An electrical machine according to claim 1, wherein the electrical conductors comprise conductive rods. [3] An electrical machine according to claim 1, wherein the at least one respective electrical conductor and the at least one respective permanent magnet contained in each recess are separated by a respective space. [4] The electric machine of claim 1, wherein the at least one respective permanent magnet contained in each recess comprises a respective first magnet and a respective second magnet, the first magnets being located between the second magnets and the electrical conductors, the first magnets having a first temperature classification and the second magnets having a second temperature classification less than the first temperature classification. [5] The electric machine of claim 1, wherein the at least one respective permanent magnet contained in each recess comprises a respective first magnet and a respective second magnet, the first magnets being located between the second magnets and the electrical conductors, the first magnets having a first coercive field strength and the second magnets having a second coercive field strength that is less than the first coercive field strength. [6] An electrical machine according to claim 3, wherein the spaces separating the electrical conductors and the permanent magnets comprise cooling passages in the rotor core. [7] An electric machine according to claim 3, wherein the spaces separating the electrical conductors and the permanent magnets contain a thermal insulator. [8] The electric machine of claim 2, further comprising an annular end ring assembly at one end of the rotor core including a first terminal conductor galvanically coupled to a first subset of the conductive bars and a second terminal conductor galvanically coupled to a second subset of the conductive bars. [9] The electric machine of claim 8, wherein the annular end ring assembly further includes a secondary coil of a rotary transformer. [10] An electric machine according to claim 9, wherein the annular end ring assembly is radially surrounded by the conductive rods, which extend beyond one end of the rotor core.

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